In the field of gas turbine engines it is necessary to protect a liner that directs flow of an extremely hot exhaust stream out of the engine. This is typically done by utilizing, high-temperature metal alloys or other high-temperature materials to form the exhaust flow liner and then supporting the liner within a surrounding exhaust duct that directs flow of cooling air between the exhaust duct and the adjacent exhaust flow liner and out of the engine with the exhaust stream. The exhaust duct provides a cooling conduit defined by the space between the liner outer surface and exhaust duct inner surface delivering cooling flow to the liner and permits usage of lower-temperature tolerant metals outside of the exhaust duct.
Modern gas turbine engines include exhaust systems having increasingly complex geometries. For example, U.S. Pat. No. 7,721,522 shows at FIGS. 2A and 2B an exhaust system that changes its geometry in operation of the engine for utilization in thrust vectoring. Additionally, gas turbine exhaust systems are subject to extraordinary mechanical stresses through vibration and thermal expansion. Some exhaust systems utilize complex profiles to acquire geometries that tailor signatures in an attempt to meet imposed propulsion system requirements. Consequently, securing or hanging the exhaust flow liner to or within the surrounding exhaust duct has typically required extraordinarily complex apparatus that are costly to manufacture, and extremely time-consuming to assemble and disassemble for servicing.
For example, U.S. Pat. No. 7,866,158 discloses an exhaust liner attachment system that provides secure hanging of the exhaust flow liner within the exhaust duct but involves complex and costly securing components that are typical of known exhaust flow liner hanging systems. U.S. Pat. No. 7,861,535 also shows an exhaust flow liner support hanger that includes self-aligning securing components, as described in the sequence of FIGS. 4-6. The components include a rod extending between ball joints secured to the exhaust duct and liner that permits limited motion of the liner relative to the exhaust duct. (The aforesaid three U.S. Patents are owned by the owner of all rights in the present disclosure.) As is apparent however, this and other known disclosures require that the rod, pin or link extending between the exhaust duct and the liner be secured to intricate attachments affixed to flow surfaces of the exhaust duct and flow liner. This in turn requires precise alignment of the attachments during assembly which is often very time consuming and extremely costly in terms of precision required in manufacturing the exhaust duct and flow liner segments to achieve necessary assembly tolerances.
Therefore, there is a need for an improved exhaust system having an exhaust flow path liner supported by a duct that minimizes costs and complexities of manufacture, assembly and disassembly.